During the eleventh year of support, 23 professional medical scientists and 11 physiology graduate students reported progress upon 66 separate research projects, including 43 publications. These reports emanated from Program-project HL08682 in which cardiovascular research deals with: 1) Cardiodynamic regulation, 2) CNS regulation of cardiopulmonary mechanisms, 3) Cardiac metabolism, 4) Physiological control systems and temperature regulation, 5) Mechanical properties of blood vessels, 6) Cardiovascular studies of mammalian hibernators, 7) Neural and Vascular Feedbacks in endocrinology, 8) Spinal regulation of vasomotor and sudomotor outflows, 9) Reinnervation of the transplanted heart, and 10) Histochemical and ultra-structural study of cardiac innervation. Transection of autonomic nerves just as they project onto the heart was found to produce complete cardiac denervation, and selective sympathectomy and/or parasympathectomy of localized portions of the heart became feasible. Thus, denervation of the SA node, without interruption of nerves to the AV node, was accomplished. Further, interruption of all cardiac innnervation except that passing by way of the ventrolateral cardiac nerve resulted in models of cardiac dysrhythmia which now permit systematic examination for clinical relevance. The interactions between contractile and elastic elements in smooth muscle of the carotid artery were investigated. Discharge patterns recorded from single cells within the respiratory control areas of the CNS were studied. The participation of the liver and endothelial system in the course of development of endotoxin shock was examined. The structure-functional relationships of pathways within the spinal cord mediating cardiovascular and cardiomotor responses were pursued, and specific functional characteristics of the motor responses associated with fiber pathways in the cord. Hibernation was maintained on a twelve month basis in a colony of ground squirrels, and some physical and chemical properties of a "trigger" substance, extracted from the plasma of hibernating animals, determined.